Control of pests such as insects has evolved from hand slaps to fly swatters to chemical insecticides, electric bug traps, glue covered strips, and other devices. Often an attractant, such as an ultraviolet light, scent or edible bait, is used to lure insects or rodents into the trap. See, for example, Phillips, U.S. Pat. No. 4,127,961, issued Dec. 5, 1978. In one common trap, an ultraviolet light attract insects onto an electrified grid which then electrocutes the insects. This device, however, sparks loudly, spatters debris, and is dangerous to humans. Mechanical traps also have drawbacks, for example, the need to lure the pest into a small space. Chemical pesticides can poison non-target species and pollute the environment.
Energy devices such as lasers have been proposed for use against insect pests. Lasers exist in several classes ranging from small, harmless beams to extremely intense beams usable as long range weapons. Japanese Patent No. 1-202,233 suggests use of a handheld laser to kill ticks, fleas and other household insects. German Patent Publication No. 3,825,389 proposes use of a laser or sound beam against flying swarms of locusts. The latter method recognizes that destroying the insects completely would require too much energy, and therefore targets a specific organ structure such as wings or sensory organs to render the insects unable to fly. Even so, the energies described are too large for practical use using the method suggested.
Like insect control, rodent and mouse control has a long history ranging from the common mousetrap to devices that use striking bars to incapacitate the rodent when it passes by; see McKee, U.S. Pat. No. 4,349,980, issued Sep. 21, 1982 and McKee, U.S. Pat. No. 4,483,094, issued Nov. 20, 1984. Poison bait pellets have also long been used to exterminate rodents. The poisoned pellets are typically scattered or placed on the ground and attract rodents looking for food.
Pest control problems are not confined to land. Recently, the Zebra mussel has invaded the Great Lakes. This creature is microscopic in its larval form and is readily drawn into water treatment plants through intake pipes. It attaches itself to a smooth surface, such as a pipe wall, and there grows over the course of two years to about a centimeter long. Huge numbers of the mussels grow together in the same location, forming a colony. The Zebra mussel's hard striped shell remains permanently attached, eventually clogging the water intake and requiring an extremely difficult, expensive cleaning operation. As a result, water plants on the Great Lakes are installing chemical and thermal Zebra mussel control systems. The former can involve release of chlorine into the lake at the intake site, a potential hazard to the lake environment. Heating or cooling lake water on a continuing basis can similarly have damaging effects on local ecosystems.
Marine pests are particularly difficult to deal with because it is hard to selectively destroy a target pest underwater without damaging the environment. The present invention addresses a number of the problems associated with conventional pest control, and further provides a method for controlling underwater pests.